This invention relates to an internal combustion engine having reduced emissions of nitrogen oxides. Much has been done in recent years to reduce the harmful products of combustion. The Environmental Protection Agency publication No. EPA-460/3-76-022 titled, "Nitrogen Oxide Control with the Delayed-Mixing, Stratified-Charge Engine Concept," authored by L. W. Evers, P. S. Myers and O. A. Uyehara present many of the methods that have been explored for controlling nitrogen oxide emissions.
Catalytic converters and other types of thermal reactors have been added to existing engines to reduce the harmful content of emissions after they leave the combustion chamber.
The U.S. Department of Commerce publication No. DOT-TSC-OST-75-56 titled, "Stratified Charge Engines" authored by Eric M. Withjack describes the operation of two open chamber stratified charge engines. One is the Ford Programmed Combustion Process (PROCO) engine. The other is the Texaco Controlled Combustion System (TCCS) engine.
The U.S. Patents to Goto (U.S. Pat. No. 3,987,776), Winkler (U.S. Pat. No. 3,658,046) and Blaser (U.S. Pat. No. 4,060,059) disclose internal combustion engines which achieve fuel mixture separation within the combustion chamber into rich and lean zones. Goto does this by successively supplying air and a fuel rich mixture by the same path. Winkler achieves a varying degree of fuel richness by centrifugal action. Blaser adds additional air to the combustion chamber so that the gas layer immediately above the piston head is fuel lean when the piston is at bottom-dead-center on the intake stroke. Subsequent engine work by Blaser after the filing of the application which issued as U.S. Pat. No. 4,060,059 is described in U.S. Naval Academy publication Number EW 8-76 titled, "The Naval Academy Heat Balanced Engine (NAHBE)", authored by R. Blasing, A. Pouring, B. Rankin and E. Keating, dated June 1976.
My invention differs from all of the above described engines. With my engine, the air-to-fuel ratio within the cylinder is progressively changed during the power stroke portion of the cycle. At ignition the air-to-fuel ratio in the main combustion chamber is preset to be on the fuel rich side. With the build up of combustion chamber pressure, as the flame front progresses across the chamber, additional fuel-lean air is added to the main chamber. This cools the flame, reduces formation of nitric and nitrous oxides and at the same time allows the combustion process to be carried to completion, thereby also reducing formation of both carbon monoxide and hydrocarbons.